1. Field of the Invention
More particularly, the present invention relates to a device being used for measuring the internal diameter of a pipe.
2. Description of the Related Art
A search of prior art record has unveiled the following patents:                1. CA 2,046,492 registered in 1991 to Barski;        2. CA 1,134,872 issued in 1982 to Passamoni;        3. CA 2,218,436 registered in 1942 to Wiercienski;        4. CA 512,624 issued in 1955 to Bissell;        5. CA 438,857 issued in 1946 to Levin;        6. CA 2,074,640 registered in 1992 to Rafilipomanana; and        7. CA 2,278,046 registered in 1997 to Prakken.        
As can be seen the patents mentioned above are probably the most relevant.